An Improved High-Resolution Wide Bandwidth ANPC Converter using VLMM and Lyapunov Stability Theory for Grid-Connected Applications

Voltage-Level Multiplier Module (VLMM) is an emerging, cost-effective design concept for Multilevel Converters (MLC) to increase the resolution of the multilevel output voltage waveform using minimum components count. The VLMM expands the operational bandwidth of MLCs by shrinking or eliminating the ac side filter. This paper uses the VLMM to design a new Wide Bandwidth Multilevel Converter (WBMLC) based on cascading Active Neutral Point Clamped (ANPC) and a five-level multiplier module for grid-tied applications. The Wide Bandwidth ANPC (WBANPC) generates a quasi-sinusoidal voltage waveform with 21-level resolution on the grid side and remarkably minifies the output filter while keeping the switching frequency very low. In addition, a robust control loop using a control-Lyapunov function and a decomposed sensorless modulator is suggested for the WBANPC to track desired objectives under a global asymptotic stability condition. Implementation results acquired under various test scenarios demonstrate that the proposed WBANPC including the voltage sensorless robust controller successfully meets the grid code requirements and causes minimum transient effects during the dynamic mode of operation of the system.